Good point. But...
Trump has spent DECADES building his public brand. EVERYONE knows who he is, and respects him as a successful manager (even if they don’t _like_ him).
That vs all other candidates who are in a mad rush to introduce themselves to all potential voters.
Q: “Trump?”
Typical A: “Yes.” or “No.”
Q: “Cruz? Bush? Carson? Christie? Fiorina? Huckabee? Kasich?”
Typical A: “Who?”
Brand recognition CERTAINLY helps, especially for contests that are still far into the future. In fact, I would say that brand recognition is most of trump’s national lead. But as one gets closer to an election, and people actually examine the candidates , brand recognition’s importance will fade, and the personal contact of good retail politics will grow in importance.